toString

Returns a string representation of the double
argument. All characters mentioned below are ASCII characters.

If the argument is NaN, the result is the string
"NaN".

Otherwise, the result is a string that represents the sign and
magnitude (absolute value) of the argument. If the sign is negative,
the first character of the result is '-'
('\u002D'); if the sign is positive, no sign character
appears in the result. As for the magnitude m:

If m is infinity, it is represented by the characters
"Infinity"; thus, positive infinity produces the result
"Infinity" and negative infinity produces the result
"-Infinity".

If m is zero, it is represented by the characters
"0.0"; thus, negative zero produces the result
"-0.0" and positive zero produces the result
"0.0".

If m is greater than or equal to 10-3 but less
than 107, then it is represented as the integer part of
m, in decimal form with no leading zeroes, followed by
'.' ('\u002E'), followed by one or
more decimal digits representing the fractional part of m.

If m is less than 10-3 or greater than or
equal to 107, then it is represented in so-called
"computerized scientific notation." Let n be the unique
integer such that 10n <= m <
10n+1; then let a be the
mathematically exact quotient of m and
10n so that 1 <= a < 10. The
magnitude is then represented as the integer part of a,
as a single decimal digit, followed by '.'
('\u002E'), followed by decimal digits
representing the fractional part of a, followed by the
letter 'E' ('\u0045'), followed
by a representation of n as a decimal integer, as
produced by the method Integer.toString(int).

How many digits must be printed for the fractional part of
m or a? There must be at least one digit to represent
the fractional part, and beyond that as many, but only as many, more
digits as are needed to uniquely distinguish the argument value from
adjacent values of type double. That is, suppose that
x is the exact mathematical value represented by the decimal
representation produced by this method for a finite nonzero argument
d. Then d must be the double value nearest
to x; or if two double values are equally close
to x, then d must be one of them and the least
significant bit of the significand of d must be 0.

To create localized string representations of a floating-point
value, use subclasses of NumberFormat.

Leading and trailing whitespace characters in s
are ignored. The rest of s should constitute a
FloatValue as described by the lexical rule:

FloatValue:

SignoptNaN

SignoptInfinity

Signopt FloatingPointLiteral

where Sign and FloatingPointLiteral are as
defined in
§3.10.2
of the Java
Language Specification. If s does not have the
form of a FloatValue, then a NumberFormatException
is thrown. Otherwise, s is regarded as
representing an exact decimal value in the usual "computerized
scientific notation"; this exact decimal value is then
conceptually converted to an "infinitely precise" binary value
that is then rounded to type double by the usual
round-to-nearest rule of IEEE 754 floating-point arithmetic,
which includes preserving the sign of a zero value. Finally, a
Double object representing this
double value is returned.

To interpret localized string representations of a
floating-point value, use subclasses of NumberFormat.

Note that trailing format specifiers, specifiers that
determine the type of a floating-point literal
(1.0f is a float value;
1.0d is a double value), do
not influence the results of this method. In other
words, the numerical value of the input string is converted
directly to the target floating-point type. The two-step
sequence of conversions, string to float followed
by float to double, is not
equivalent to converting a string directly to
double. For example, the float
literal 0.1f is equal to the double
value 0.10000000149011612; the float
literal 0.1f represents a different numerical
value than the double literal
0.1. (The numerical value 0.1 cannot be exactly
represented in a binary floating-point number.)

doubleValue

hashCode

public int hashCode()

Returns a hash code for this Double object. The
result is the exclusive OR of the two halves of the
long integer bit representation, exactly as
produced by the method doubleToLongBits(double), of
the primitive double value represented by this
Double object. That is, the hash code is the value
of the expression:

equals

Compares this object against the specified object. The result
is true if and only if the argument is not
null and is a Double object that
represents a double that has the same value as the
double represented by this object. For this
purpose, two double values are considered to be
the same if and only if the method doubleToLongBits(double) returns the identical
long value when applied to each.

Note that in most cases, for two instances of class
Double, d1 and d2, the
value of d1.equals(d2) is true if and
only if

d1.doubleValue() == d2.doubleValue()

also has the value true. However, there are two
exceptions:

If d1 and d2 both represent
Double.NaN, then the equals method
returns true, even though
Double.NaN==Double.NaN has the value
false.

If d1 represents +0.0 while
d2 represents -0.0, or vice versa,
the equal test has the value false,
even though +0.0==-0.0 has the value true.

doubleToLongBits

public static long doubleToLongBits(double value)

Returns a representation of the specified floating-point value
according to the IEEE 754 floating-point "double
format" bit layout.

Bit 63 (the bit that is selected by the mask
0x8000000000000000L) represents the sign of the
floating-point number. Bits
62-52 (the bits that are selected by the mask
0x7ff0000000000000L) represent the exponent. Bits 51-0
(the bits that are selected by the mask
0x000fffffffffffffL) represent the significand
(sometimes called the mantissa) of the floating-point number.

If the argument is positive infinity, the result is
0x7ff0000000000000L.

If the argument is negative infinity, the result is
0xfff0000000000000L.

If the argument is NaN, the result is
0x7ff8000000000000L.

In all cases, the result is a long integer that, when
given to the longBitsToDouble(long) method, will produce a
floating-point value the same as the argument to
doubleToLongBits (except all NaN values are
collapsed to a single "canonical" NaN value).

Bit 63 (the bit that is selected by the mask
0x8000000000000000L) represents the sign of the
floating-point number. Bits
62-52 (the bits that are selected by the mask
0x7ff0000000000000L) represent the exponent. Bits 51-0
(the bits that are selected by the mask
0x000fffffffffffffL) represent the significand
(sometimes called the mantissa) of the floating-point number.

If the argument is positive infinity, the result is
0x7ff0000000000000L.

If the argument is negative infinity, the result is
0xfff0000000000000L.

If the argument is NaN, the result is the long
integer representing the actual NaN value. Unlike the
doubleToLongBits method,
doubleToRawLongBits does not collapse all the bit
patterns encoding a NaN to a single "canonical" NaN
value.

In all cases, the result is a long integer that,
when given to the longBitsToDouble(long) method, will
produce a floating-point value the same as the argument to
doubleToRawLongBits.

Parameters:

value - a double precision floating-point number.

Returns:

the bits that represent the floating-point number.

longBitsToDouble

public static double longBitsToDouble(long bits)

Returns the double value corresponding to a given
bit representation.
The argument is considered to be a representation of a
floating-point value according to the IEEE 754 floating-point
"double format" bit layout.

If the argument is 0x7ff0000000000000L, the result
is positive infinity.

If the argument is 0xfff0000000000000L, the result
is negative infinity.

If the argument is any value in the range
0x7ff0000000000001L through
0x7fffffffffffffffL or in the range
0xfff0000000000001L through
0xffffffffffffffffL, the result is a NaN. No IEEE
754 floating-point operation provided by Java can distinguish
between two NaN values of the same type with different bit
patterns. Distinct values of NaN are only distinguishable by
use of the Double.doubleToRawLongBits method.

In all other cases, let s, e, and m be three
values that can be computed from the argument:

Then the floating-point result equals the value of the mathematical
expression s·m·2e-1075.

Note that this method may not be able to return a
double NaN with exactly same bit pattern as the
long argument. IEEE 754 distinguishes between two
kinds of NaNs, quiet NaNs and signaling NaNs. The
differences between the two kinds of NaN are generally not
visible in Java. Arithmetic operations on signaling NaNs turn
them into quiet NaNs with a different, but often similar, bit
pattern. However, on some processors merely copying a
signaling NaN also performs that conversion. In particular,
copying a signaling NaN to return it to the calling method
may perform this conversion. So longBitsToDouble
may not be able to return a double with a
signaling NaN bit pattern. Consequently, for some
long values,
doubleToRawLongBits(longBitsToDouble(start)) may
not equal start. Moreover, which
particular bit patterns represent signaling NaNs is platform
dependent; although all NaN bit patterns, quiet or signaling,
must be in the NaN range identified above.

Parameters:

bits - any long integer.

Returns:

the double floating-point value with the same
bit pattern.

compareTo

Compares two Double objects numerically. There
are two ways in which comparisons performed by this method
differ from those performed by the Java language numerical
comparison operators (<, <=, ==, >= >)
when applied to primitive double values:

Double.NaN is considered by this method
to be equal to itself and greater than all other
double values (including
Double.POSITIVE_INFINITY).

0.0d is considered by this method to be greater
than -0.0d.

This ensures that Double.compareTo(Object) (which
forwards its behavior to this method) obeys the general
contract for Comparable.compareTo, and that the
natural order on Doubles is consistent
with equals.

Parameters:

anotherDouble - the Double to be compared.

Returns:

the value 0 if anotherDouble is
numerically equal to this Double; a value
less than 0 if this Double
is numerically less than anotherDouble;
and a value greater than 0 if this
Double is numerically greater than
anotherDouble.

compareTo

Compares this Double object to another object. If
the object is a Double, this function behaves like
compareTo(Double). Otherwise, it throws a
ClassCastException (as Double objects
are comparable only to other Double objects).

the value 0 if the argument is a
Double numerically equal to this
Double; a value less than 0
if the argument is a Double numerically
greater than this Double; and a value
greater than 0 if the argument is a
Double numerically less than this
Double.

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